The invention relates to a short stroke actuator for producing a holding or retaining force on a workpiece and comprising a pressure space which is adapted to be put under pressure for operation of the actuator.
If a workpiece is to be machined on a machine tool it first has to be located on the work table of the machine tool and then clamped or otherwise fixed in place so that it is not dislodged during the ensuing machining operation, as for example the boring of a hole in the workpiece. It is more especially in mass production techniques that workpieces are held in place by an array of short stroke actuators designed to be mounted on the machine tool, and whose piston rods are moved outwards when the actuator is supplied with fluid under pressure, and which push the work against an abutment. The number of clamping cylinders then needed in the array will be dependent on the dimensions of the respective workpiece. If the work is in the form of a sheet or broad, it will be necessary to provide a plurality of clamping cylinders arrayed in a row so that they may engage the nearest edge of the work at spaced positions.
However, such a multiple arrangement of clamping cylinders is a relatively complex piece of equipment or "hardware" and is therefore high in price. Furthermore, during retooling the production facilities it is necessary to separately adjust the positions of the clamping cylinders so that such adaptation of the production devices is slowed down. A further point to be considered is that the clamping cylinders only engage the work at separate points rather than over large areas so that there is a high concentration of surface force in order to achieve the necessary clamping or retaining effect. If the work is made of wood, the surface may then be damaged and be scored by the piston rods of the actuators.